Method of catalyst manufacture

ABSTRACT

A method of manufacturing a supported metal phthalocyanine catalyst is disclosed. An aqueous dispersion of a metal phthalocyanine comprising a soluble acid amide is prepared, and a solid adsorptive support contacted therewith at conditions to adsorb at least a catalytic amount of said metal phthalocyanine thereon. The resulting composite is subsequently dried.

This invention relates to a novel method for the manufacture of asupported metal phthalocyanine catalyst particularly useful in thetreatment of a sour petroleum distillate or fraction. Processes for thetreatment of a sour petroleum distillate wherein said distillate ispassed in contact with a supported metal phthalocyanine catalystdisposed as a fixed bed in a treating or reaction zone, have become wellknown and widely accepted in the industry. The treating process istypically designed to effect the catalytic oxidation of offensivemercaptans contained in the sour petroleum distillate with the formationof innocuous disulfides. The oxidizing agent is most often air admixedwith the sour petroleum distillate to be treated. Gasoline, includingnatural, straight run and cracked gasolines, is the most frequentlytreated sour petroleum distillate. Other sour petroleum distillatesinclude the normally gaseous petroleum fractions as well as naphtha,kerosine, jet fuel, fuel oil, lube oil, and the like.

In the manufacture of a supported phthalocyanine catalyst, it is thepractice to adsorb the phthalocyanine on an adsorptive support from asolution and/or dispersion thereof. Methanolic solutions or dispersionshave heretofore provided a most active catalytic composite. However,methanol has become increasingly objectionable in that it is relativelyexpensive, toxic, and difficult to dispose of. Aqueous solutions bythemselves afford a relatively poor distribution of the phthalocyanineon the adsorptive support and quality control is difficult to achieve.While the prior art, noteably U.S. Pat. No. 3,108,081, suggests thatimproved solubility in aqueous solution is accomplished by the inclusionof a strong base, for example, ammonia, ammonium hydroxide, and thelike, it has now been found that a catalytic composite of substantiallygreater activity results when the additive is instead substantiallyneutral or a weak base as herein defined.

Thus, in one of its broad aspects, the present invention embodies amethod of catalyst manufacture which comprises preparing an aqueousdispersion of a metal phthalocyanine comprising a soluble acid amide;contacting a solid adsorptive support with said dispersion at conditionsto adsorb at least a catalytic amount of said metal phthalocyaninethereon; and drying the resulting composite.

A further embodiment is in a method of catalyst manufacture whichcomprises preparing an aqueous dispersion of cobalt phthalocyaninemonosulfonate comprising a soluble diamide; contacting a solidadsorptive support with said dispersion at conditions to adsorb at leasta catalytic amount of said phthalocyanine thereon; and drying theresulting composite.

One of the more specific embodiments is in a method of catalystmanufacture which comprises preparing an aqueous dispersion of cobaltphthalocyanine monosulfonate and urea; contacting an activated carbonsupport with said dispersion at conditions to adsorb from about 0.1 toabout 10 wt. % cobalt phthalocyanine thereon; and drying the resultingcomposite.

In addition to the relatively inexpensive, non-toxic attributes of theacid amides employed herein, a further significant advantage resultingfrom the practice of this invention is in the biodegradable nature of,for example, urea, to substantially obviate the disposal problemencountered in the use of methanol.

Other objects and embodiments of this invention will become apparent inthe following detailed specification.

Pursuant to the method of this invention, a metal phthalocyanine isadsorbed on a solid adsorbent support from an aqueous dispersion of saidphthalocyanine, said dispersion further containing a soluble acid amide.The method of the present invention is applicable to the manufacture ofa catalytic composite comprising any of the various metalphthalocyanines, for example, magnesium, titanium, hafnium, vanadium,tantalum, molybdenum, manganese, iron, cobalt, nickel, platinum,palladium, copper, silver, zinc and tin phthalocyanine, and the like.Cobalt phthalocyanine and vanadium phthalocyanine are particularlypreferred metal phthalocyanines. The metal phthalocyanine is preferablyemployed herein as a derivative thereof, the commercially availablesulfonated derivatives, for example, cobalt phthalocyaninemonosulfonate, cobalt phthalocyanine disulfonate, or mixtures thereof,being particularly preferred. The sulfonated derivatives may beprepared, for example, by reacting cobalt, vanadium or other metalphthalocyanine with fuming sulfuric acid. While the sulfonatedderivatives are preferred, it is understood that other derivatives,particularly the carboxylated derivatives, may be employed. Thecarboxylated derivatives are readily prepared by the action oftrichloroacetic acid on the metal phthalocyanine.

The acid amides of this invention are intended to include the watersoluble, essentially neutral, aliphatic primary amides, for example,formamide, acetamide, propionamide, n-butyramide, isobutyramide,valeramide, and the like, and also the corresponding water solublediamides, particularly malonamide and carbamide (urea). The selectedacid amide, preferably urea, is advantageously first prepared in aqueoussolution in sufficient amount to provide from about 2 to about 10 wt. %acid amide therein. From about a 4 to about a 6 wt. % concentration isparticularly useful. In any case, the selected metal phthalocyanine issubsequently dispersed in the acid amide solution, preferably in anamount to provide a metal phthalocyanine/acid amide weight ratio of fromabout 1:1 to about 2:1. The resulting dispersion may be subsequentlydiluted to a larger volume more commensurate with the volume of solidadsorbent on which the metal phthalocyanine is to be adsorbed.

The solid adsorbent supports herein contemplated include any of thevarious and well-known adsorbent solid materials generally utilized as acatalyst support. Preferred adsorbent materials include the variouscharcoals produced by the destructive distillation of wood, peat,lignite, nutshells, bones, and other carbonaceous matter, and preferablysuch charcoals as have been heat treated, or chemically treated, orboth, to form a highly porous particle structure of increased adsorbentcapacity, and generally defined as activated carbon. Said adsorbentmaterials also include the naturally occurring clays and silicates, forexample, diatomaceous earth, fuller's earth, kieselguhr, attapulgusclay, feldspar, montmorillonite, halloysite, kaolin, and the like, andalso the naturally occurring or synthetically prepared refractoryinorganic oxides such as alumina, silica, zirconia, thoria, boria, etc.,or combinations thereof like silica-alumina, silica-zirconia,alumina-zirconia, etc. Any particular solid adsorbent material isselected with regard to its stability under conditions of its intendeduse. For example, in the treatment of a sour petroleum distillateheretofore described, the solid adsorbent carrier material should beinsoluble in, and otherwise inert to, the hereinafter described aqueouscaustic solutions and the petroleum distillate at conditions existing inthe treating zone. In the latter case, charcoal, and particularlyactivated carbon, is preferred because of its capacity for metalphthalocyanine and because of its stability under treating conditions.However, it should be observed that the method of this invention is alsoapplicable to the preparation of metal phthalocyanine composited withany of the other well-known solid adsorbent carrier materials,particularly the refractory inorganic oxide.

The metal phthalocyanine may be adsorbed onto the solid adsorbentsupport in any conventional or otherwise convenient manner. In general,the support or carrier material, in the form of spheres, pills, pellets,granules, or other particles of uniform or irregular shape, is dipped,soaked, suspended, or otherwise immersed in the described aqueousdispersion, or the aqueous dispersion may be sprayed onto, poured over,or otherwise contacted with the adsorbent support. In any case, theexcess solution and/or dispersion is separated and the resultingcomposite allowed to dry under ambient temperature conditions, or driedat an elevated temperature in an oven, in a flow of hot gases, or in anyother suitable manner.

It is generally preferable to adsorb as much metal phthalocyanine on theadsorbent support as will form a stable catalytic composite, although alesser amount in the range of from about 0.1 to about 10 wt. % affords asuitably active catalytic composite. One convenient method of catalystpreparation comprises passing the aqueous metal phthalocyaninedispersion through a bed of the adsorbent support predisposed in a sourpetroleum distillate treating zone in order to form the catalyticcomposite in situ. This method allows the aqueous dispersion to berecycled one or more times to achieve a desired concentration of themetal phthalocyanine on the adsorbent support. In still another method,the adsorbent support may be predisposed in said treating chamber andthe chamber thereafter filled with the aqueous metal phthalocyaninedispersion to soak the support for a predetermined period, therebyforming the catalytic composite in situ.

In the sweetening of a sour petroleum distillate as herein contemplated,the offensive mercaptans contained therein are oxidized to formdisulfides. This oxidation reaction is effected in the presence of analkaline reagent which is admixed with the sour petroleum distillate andpassed in contact with the solid catalytic composite. Any suitablealkaline reagent may be employed, although an aqueous caustic solutionis preferred. Other suitable alkaline solutions particularly includeaqueous potassium hydroxide solutions, but also aqueous solutions oflithium hydroxide, rubidium hydroxide, and cesium hydroxide. Similarly,while water is a preferred solvent for the alkaline reagent, othersolvents may be employed including, for example, alcohols, andespecially methanol, ethanol, propanol, butanol, etc., ketones includingacetone, methylethyl ketone, etc. In some cases, the treating iseffected in the presence of both an aqueous solution of the alkalinereagent and an alcohol, particularly methanol or ethanol or solutizersor solubilizers including, for example, phenols, cresols, butyric acid,etc.

The sweetening process is usually effected at ambient temperatureconditions although elevated temperatures generally not in excess ofabout 300° F. may be used. The process may be effected at a pressure ofup to about 1000 psi or more, although atmospheric, or at substantiallyatmospheric, pressures are entirely suitable. Contact times equivalentto a liquid hourly space velocity of from about 1 to about 100 or moreare effective to achieve a desired reduction in the mercaptan content ofa sour petroleum distillate, and optimum contact time being dependent onthe size of the treating zone, the quantity of catalyst containedtherein, and the sour petroleum distillate being treated.

As previously stated, sweetening of the sour petroleum distillate iseffected by oxidizing the mercaptan content thereof to disulfides.Accordingly, the process is effected in the presence of an oxidizingagent, preferably air, although oxygen or other oxygen-containing agentsmay be employed. The mixture of petroleum distillate, alkaline reagentand oxidizing agent is passed upwardly or downwardly through thecatalyst bed. In some cases, the air may be passed countercurrently tothe petroleum distillate. In still other cases, the petroleum distillateand alkaline reagent may be introduced separately into the treatingzone.

In many instances, the sour petroleum distillate, and especiallygasoline, is first treated with an alkaline reagent solution in order toremove a major portion of the mercaptan prior to further treating in themanner hereinbefore described. Any suitable alkaline reagent, andparticularly sodium hydroxide or potassium hydroxide, solution isutilized. This removes a major portion of the mercaptans but leaves adistillate which is sour. For the conversion of the mercaptans iseffected in the presence of the catalytic composite herein described.

Subsequent to the extraction of mercaptans, an alkaline reagent solutioncontaining the mercaptans as mercaptides is subjected to regeneration.In a preferred operation, this regeneration is effected by oxidation inthe presence of a suitable catalyst to regenerate the alkaline metalhydroxide and to form disulfides. As another advantage to the catalystcomposite of the present invention, regeneration of the used alkalinesolution is effected in the presence of the catalyst and air, oxygen orother suitable oxidizing agent.

The catalytic composite perpared in accordance with the method of thisinvention is both active and stable. Accordingly, the catalyticcomposite may be employed in a fixed bed for the treatment of largevolumes of a sour petroleum distillate. Although the metalphthalocyanine is somewhat soluble in alkaline solution, it isnevertheless retained on the solid adsorbent support. However, in theevent that any of the metal phthalocyanine is leaked from the support,or otherwise carried away in the alkaline solution, it may be readilyrecycled in said solution for reuse in the sweetening process. However,it is in some cases desirable to introduce additional metalphthalocyanine for adsorption on the solid support in the manner hereindescribed.

The following examples are presented in illustration of one preferredembodiment of this invention and are not intended as an undue limitationon the generally broad scope of the invention as set out in the appendedclaims.

EXAMPLE I

Cobalt phthalocyanine monosulfonate was impregnated on Norit charcoal.The charcoal particles of this and subsequent examples had an apparentbulk density of about 0.25 grams per cubic centimeter and a particlesize in the 10×30 mesh range. About 150 milligrams of the cobaltphthalocyanine monosulfonate was stirred in 100 milliliters of methanolfor 5 minutes. The mixture was then allowed to settle and the methanolsolution decanted into a 400 milliliter beaker. The remaining cobaltphthalocyanine monosulfonate was again stirred for about 5 minutes with100 milliliters of methanol added thereto, the mixture allowed tosettle, and the methanol solution decanted into the 400 milliliterbeaker. The process was repeated a third time to dissolve or disperseall of the remaining cobalt phthalocyanine monosulfonate in methanol.The methanol-cobalt phthalocyanine monosulfonate dispersion, comprising150 milligrams of cobalt phthalocyanine monosulfonate dispersed in 300milliliters of methanol, was then added to an Erlenmeyer flaskcontaining 100 cc of the charcoal particles. A visual inspectionindicated a very good dispersion of cobalt phthalocyanine monosulfonatein the methanol. The mixture was stirred or shaken for about 3 minutes,allowed to stand under quiescent conditions for about 1 hour, andthereafter evaporated to dryness on a steam bath. The impregnatedcharcoal was subsequently oven-dried at 200° F. for 2 hours.

EXAMPLE II

Charcoal particles, substantially as described in Example I, were againimpregnated with cobalt phthalocyanine monosulfonate. In this example,150 milligrams of the cobalt phthalocyanine monosulfonate was dispersedin 25 milliliters of water containing 1 milliliter of 28% aqueousammonium hydroxide solution, and the dispersion was then diluted toabout 125 milliliters with deionized water. The dispersion was stirredfor about 5 minutes and added to an Erlenmeyer flask containing 100 ccof the fresh charcoal. A visual examination indicated a very gooddispersion of cobalt phthalocyanine monosulfonate in the water. Theaqueous ammonium hydroxide-cobalt phthalocyanine dispersion was thenstirred or shaken for about 3 minutes in contact with the charcoal. Themixture was allowed to stand for 1 hour and the aqueous dispersionthereafter evaporated to dryness in contact with the charcoal utilizinga steam bath.

EXAMPLE III

In this example, charcoal particles substantially as described in theprevious examples, were impregnated with cobalt phthalocyaninemonosulfonate from an aqueous dispersion thereof. The aqueous dispersionwas prepared by admixing 150 milligrams of the cobalt phthalocyaninemonosulfonate with about 5 milliliters of deionized water to produce aslurry, and then diluting the aqueous dispersion to about 125milliliters with deionized water. The dispersion was stirred for about 5minutes and then poured over 150 cc of the charcoal particles containedin a 500 milliliter Erlenmeyer flask. The cobalt phthalocyaninedispersion was very poor by visual inspection. The aqueous cobaltphthalocyanine monosulfonate dispersion was stirred or shaken in contactwith the charcoal for about 3 minutes. The mixture was allowed to standfor about 1 hour, and thereafter evaporated to dryness over a steambath.

EXAMPLE IV

In accordance with a preferred embodiment of this invention, 150milligrams of cobalt phthalocyanine monosulfonate was dispersed in 5milliliters of deionized water containing 0.2 wt. % urea dissolvedtherein. The dispersion was stirred for about 5 minutes to produce aslurry, diluted to about 125 milliliters with deionized water, andstirred an additional 5 minutes. The cobalt phthalocyanine monosulfonatedispersion was, by visual inspection, especially good. The resultingaqueous urea-cobalt phthalocyanine monosulfonate dispersion was stirredor shaken in contact with the charcoal particles for about 3 minutes,allowed to stand for about 1 hour, and thereafter evaporated to drynesson a steam bath.

A comparative evaluation of the catalytic composite on the foregoingexamples was effected in the following manner. In each case, 100 cubiccentimeters of the catalytic composite was loaded into a 22 millimeterO.B. tubular glass reactor. The resulting catalyst bed was about 41millimeters in length and rested on a fine mesh screen on top of glassbeads. The catalyst bed was flooded with aqueous 10° Baume sodiumhydroxide solution and then drained. A sour feed stock, containing 759ppm mercaptans sulfur, was dripped onto the catalyst bed at a rate of100 milliliters per hour. Air, at the rate of about 6240 cc per hour, atstandard conditions, was added concurrently with the sour feed stock.The reactor effluent was analyzed periodically for mercaptan content.The results are compared in Table I below.

                  TABLE I                                                         ______________________________________                                        RSH-S Wt. PPM                                                                 Catalyst                                                                              0 Hr.  1 Hr.  5 Hrs. 10 Hrs.                                                                              15 Hrs.                                                                              20 Hrs.                            ______________________________________                                        1       759    6      8      12     19     24                                 2       759    10     10     15     20     24                                 3       759    9      9      12     15     18                                 4       759    10     8       9     12     16                                 ______________________________________                                    

The method of manufacture presented herein offers more than a usefulalternative overcoming the heretofore mentioned limitations of prior artmanufacturing methods. The catalytic composite manufactured inaccordance with the novel method of this invention exhibits asignificant improvement in activity with respect to the conversion ofmercaptans contained in a sour petroleum distillate. The activityimprovement enables the effective treatment of those sour petroleumdistillates comprising the more difficultly oxidizable mercaptans andhighly resistant to the sweetening process.

I claim as my invention:
 1. A method of catalyst manufacture whichcomprises:a. preparing an aqueous dispersion of a metal phthalocyaninecontaining a water soluble diamide selected from the group consisting ofmalonamide and urea, wherein said metal phthalocyanine to said diamideweight ratio is 1:1 to about 2:1; b. contacting a solid adsorptivesupport with said dispersion at conditions to adsorb at least acatalytic amount of said metal phthalocyanine thereon; and c. drying theresulting composite.
 2. The method of claim 1 further characterized inthat said metal phthalocyanine is a vanadium phthalocyanine.
 3. Themethod of claim 1 further characterized in that said metalphthalocyanine is a cobalt phthalocyanine.
 4. The method of claim 1further characterized in that said metal phthalocyanine is a cobaltphthalocyanine sulfonate.
 5. The method of claim 1 further characterizedin that said metal phthalocyanine is cobalt phthalocyaninemonosulfonate.
 6. The method of claim 1 further characterized in thatsaid support is contacted with said solution at conditions to adsorbfrom about 0.1 to about 10 wt. % metal phthalocyanine thereon.
 7. Themethod of claim 1 further characterized in that said adsorptive supportis an activated carbon.